Michael Phelps Stars in Under Armour Ad

Olympic swimmer Michael Phelps, who grew up in Rodgers Forge, stars in a new Under Armour ad that brought him and his fiancee to tears.

"That commercial shows a lot of amazing things about me that probably the world has never seen," Phelps said after watching the ad.

The Under Armour ad campaign called "Rule Yourself" has featured other athletes including the USA Gymnastics women's team, according to a statement from Under Armour, which said the point was to show the effort that goes into training.

In the 91-second spot starring Phelps, he is seen swimming in an illuminated pool surrounded by darkness and physically pushing himself to the point of shivering.

"In our eyes, there is no one who can tell the story of what it takes to be successful in training better than Michael Phelps," Under Armour Senior Vice President of Global Brand Marketing Adrienne Lofton said.

Phelps, who is the most decorated Olympian of all time with 18 gold medals, is currently preparing for what he has said will be his final Olympics, in Rio de Janeiro.

"Despite Michael's visibility in the public sphere, it is the work he puts in behind the scenes that truly defines his quest for greatness," Lofton said. "By shining a light on those moments in this campaign, we hope to inspire all athletes to push beyond their perceived limitations."

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Under Armour posted a clip showing the Phelps and his fiancee, Nicole Johnson, seeing the ad spot for the first time, which was emotional for both parties.

Brushing away a tear, Johnson said: "It's knowing what's sacrificed, and being able to see it on a screen."